Police and paramilitary forces surrounded the exchange in Karachi during a firefight in which at least three security officers and four attackers were killed.

Pakistan’s ambassador to Afghanistan said on Monday that negotiations between the Afghan government and the insurgent Taliban were expected to begin soon but that the release of 5,000 prisoners and a reduction of violence were the final hurdles.

The government and the Taliban pointed blame at each other in the latest attack. But in this war, there is diminishing clarity on who is to blame for the bodies piling up.